Gastric cancer is thought to result from a combination of environmental factors and the accumulation of specific genetic alterations due to increasing genetic instability, and consequently affects mainly older patients.

Microscopical subtypes

Histologically, gastric carcinoma demonstrates marked heterogeneity at both architectural and cytologic level, often with co-existence of several histologic elements.

Over the past half century the histologic classification of gastric carcinoma has been largely based on Lauren’s criteria, in which intestinal type and diffuse type adenocarcinoma are the two major histologic subtypes, plus indeterminate type as uncommon variant.

The relative frequencies are approximately: 54% for intestinal type, 32% for the diffuse type, 15% for the indeterminate type.

There are indications that the diffuse type gastric carcinoma is more often seen in female and young individuals, while the intestinal type adenocarcinoma is more often associated with intestinal metaplasia and Helicobacter pylori infection.

Less than 10% of patients present with the disease before 45 years of age (early onset gastric carcinoma) and these patients are believed to develop gastric carcinomas with a molecular genetic profile differing from that of sporadic carcinomas occurring at a later age. In young patients, the role of genetics is presumably greater than in older patients, with less of an impact from environmental carcinogens.

As a result, hereditary gastric cancers and early onset gastric cancers can provide vital information about molecular genetic pathways in sporadic cancers and may aid in the unraveling of gastric carcinogenesis.